Conventional cylinder head gaskets generally include armoring around the combustion openings. For example, U.S. Pat. No. 4,434,989 to Beyer et al. discloses a gasket with a U-shaped armor framing the combustion opening. Many such gaskets also usually employ a steel core and facing layers thereon. The core may be a solid core, in which event the facing layers are adhesively bonded to the core. Alternatively, the core may be a perforated steel core, in which case the facing layers are usually mechanically clinched to the core. The zone around the cylinder bore and in contact with the combustion gases usually consists of a steel or stainless steel wrap or armor for sealing the joint between the engine head and block and for protecting the facing layers,
One purpose of the armor wrap is to concentrate stresses at the combustion openings in the zones between the engine head and block, thereby to seal against the escape of high temperature and pressure combustion gases. The use of the armor wraps has also been viewed as critical to protecting gasket facings from the effects of high temperature, and is particularly important for facings employing temperature sensitive materials such as rubbers which can burn and char, and which can degrade at the high temperatures at which internal combustion engines operate.
It would be desirable for cost savings and for other reasons to avoid the use of armor wraps at combustion openings if other ways i:o provide the necessary stress concentration could be found to provide effective sealing around the combustion openings.